Development of the eyeball during fetal life.

Two hundred fifty-two undamaged human fetuses without external malformations were supplied by the human embryo and fetus collection of the Department of Anatomy, Kyoto University. The sagittal, vertical and horizontal diameters of the eyeball were measured by micrometer, and the transverse, vertical and horizontal circumferences of the eyeball were measured by mapmeter from photographs of the side views of the eye. All the diameters of the eyeball showed a parallel linear increase from the 12th to the 40th week of menstrual age. The increase of circumferences of the eyeball paralleled each other throughout the 12th to the 40th week. It is significant that the sagittal diameter of the eyeball is shorter than the vertical and transverse diameters during fetal life. The vertical meridian circumference of the eyeball is also shorter than the transverse and horizontal meridian circumferences during fetal life. These findings suggest that many infants are apt to have hyperopia at birth.